Cardiac arrest, exposure to high voltage power lines, and other trauma to the body can result in heart fibrillation which is the rapid and uncoordinated contraction of the cardiac muscle. The use of external defibrillators to restore the heartbeat to its normal pace through the application of an electrical shock is a well recognized and important tool for resuscitating patients. External defibrillation is typically used in emergency settings in which the patient is unconscious.
Automated external defibrillators (AEDs) are used by first-responders, emergency medical technicians and other trained personnel to resuscitate patients in cardiac fibrillation. The American Heart Association has identified early defibrillation as the key link in the Chain of Survival from sudden cardiac arrest. Therefore, it is important that AEDs be ready for use on a moment's notice and that they be simple to use.
To help ensure a high level of confidence that they will be operational when needed, AEDs perform self tests to check for the presence and connection of defibrillator electrodes, battery charger state, the function of the high voltage circuit, and the function of the digital control system. If maintenance is needed, audio alarms and visual signals are given. To ensure the AED is fast and easy to use, it gives voice prompts to guide the user through the approved cardiac resuscitation process step by step. AEDs use built-in speakers to sound these audible alarms and voice prompts.
AEDs are used anywhere an emergency occurs, therefore, indoor and outdoor operation is important. Outdoor use requires that openings in the AED housing be substantially water resistant to prevent damage to internal electrical components due to water contact. However, current methods for weatherproofing speaker openings in AEDs may reduce speaker output quality, which in turn makes current AEDs sound like computers. This is undesirable in the high stress atmosphere of a cardiac arrest rescue, where a human-like voice giving instructions would be more clear, understandable, soothing, and calming to the person performing the intense life saving procedure.
Data collected on response time and activities at the emergency scene can be useful for analyzing a number of critical aspects of patient resuscitation. These include evaluating response procedures, training responders using real-life scenarios, and evaluating patient response to known treatment. It would be desirable to provide an AED capable of recording activities at the emergency scene for later use. Furthermore, it would be desirable to provide an AED that would clearly record ambient activities in all environmental conditions.